What kind of computer operating system do I need in order to use Messenger for Windows?You can set up the app if you use Windows 7 on your computer.

In fact, it runs perfectly well under Windows Vista with the .NET Framework installed. In Windows XP, it crashes on load (though the notification area icon appears first):

Looking at the executable in .NET Reflector, the program uses the functions DwmSetWindowAttribute and DwmExtendFrameIntoClientArea, which are not available in Windows XP. I suspect that adding support for that operating system wouldn’t be very difficult, however, as the program is little more than a couple of WebBrowser controls (the heavy lifting is not done on the client side).

Given that Facebook decided not to support Windows XP, the least they could do is use a task dialog instead of this:

If you look closely, you’ll notice that the font is Microsoft Sans Serif, not Segoe UI (the latter is the user interface font in Windows Vista and newer – MS Sans Serif hasn’t been the default since Windows ME!). This is largely Microsoft’s fault – MS Sans Serif is the default font in the Windows Forms designer even in Visual Studio 2010 (and the issue has been around for a long time) – but it’s something that the Facebook developers should have picked up on.

I was disappointed to see that the application is installed to the ‘local application data’ folder (C:Users<User>AppDataLocal in Vista and newer) instead of Program Files. I guess when Google decides it’s acceptable to install Google Chrome in %appdata%, everything is permitted. (Microsoft itself is hardly blameless – ClickOnce applications are installed to somewhere non-standard.)